1. Technical Field
The invention generally relates to the field of communications networks and more particularly to an object transfer from a first network component via an intermediate component to a second network component, the second network component being remote from the first network component.
2. Description of the Prior Art
The transfer of information over modern communications networks like the public Internet or internal networks is based on specific transfer protocols. The World Wide Web for example, which constitutes a major aspect of the Internet, uses the Hyper Text Transfer Protocol (HTTP) for exchanging files comprising text, images, sound, video, and other contents.
Any WWW server contains, in addition to the files it can serve, an HTTP component that is designed to wait for HTTP requests and to handle them when they arrive. A WWW browser can be considered as an HTTP client that is configured to send HTTP requests to WWW servers. Whenever a user of the browser enters a file request by either “opening” a WWW file (by typing in a Uniform Resource Locator (URL)) or by clicking on a hyper text link, the browser builds a corresponding HTTP request for the file and sends it to the destination address. The HTTP component in the destination server receives the HTTP request and returns the requested file.
The requested file may be constituted by a Hyper Text Mark up Language (HTML) page that includes HTML code. When the browser receives the HTML page from the server and detects that the HTML code, which can be considered as an object itself, includes further objects such as (background) images, sounds, scripts or HTML frames, the browser issues further HTTP requests to the server in order to fetch the further objects which are included in the HTML code. Upon receipt of the further HTTP requests, the server sends HTTP responses including the requested objects like images to the browser. As becomes apparent from FIG. 1, the HTTP responses are sent from the server to the browser running on the client in the same order as the browser has issued the HTTP requests.
The order in which any additional objects included in the HTML code of the HTML page are requested by the browser usually depends on how the HTML page was written. For example an object that is included at the beginning of the HTML code is not necessarily displayed at the top of the HTML page because features such as tables, layers and frames allow the HTML author to use complex layouts. In addition, the order in which a browser issues HTTP requests depends also on internal browser algorithms. For example some browsers use complex heuristics for generating the HTTP requests by starting with requesting the first four objects as they appear in the HTML code of the page. After the first four objects have been requested, every second object starting from the top of the area that is currently visible to the user is requested, then every fourth object and so on. Other browsers use a simpler algorithm that requests the objects one by one as they appear in the HTML code. From the above it becomes apparent that it is usually difficult to predict the order in which HTTP requests for objects referred to in an HTML code are generated.
Moreover, it is difficult to predict the order in which requested objects are received by the browser. Although the current HTTP standard (HTTP/1.1) requires that on each Transfer Control Protocol (TCP) connection the HTTP responses are sent from the server to the browser in the same order as the HTTP requests are received by the server, the order in which HTTP responses are received becomes unpredictable as soon as more than one connection is opened to the server. The reason therefore is the fact that due to varying network conditions and different request processing times, some connections may transfer HTTP responses faster than others.
There is a need for a method and a device that enable an improved transfer of objects from a first network component to a second network component which is remote from the first network component.